The State Department confirmed it offered millions of dollars to the captain of an Iranian oil tanker to divert the vessel to a country that would be able to seize it on behalf of the United States. The Financial Times revealed Wednesday State Department official Brian Hook sent an email that read, “I am writing with good news,” before attempting to bribe the captain of the Adrian Darya 1. The tanker became the focus of growing diplomatic tensions between Iran and the U.S. over the summer after it was impounded by British authorities in Gibraltar in July on suspicion of transporting oil to Syria. It was released last month after Gibraltar rejected a U.S. request to keep detaining the ship.

Iranian Foreign Minister Javad Zarif responded to the report by tweeting, “Having failed at piracy, the US resorts to outright blackmail—deliver us Iran’s oil and receive several million dollars or be sanctioned yourself. Sounds very similar to the Oval Office invitation I received a few weeks back.”

The news came as the U.S. imposed yet more sanctions on Iran Wednesday, blacklisting an oil shipping network. A senior Trump official also indicated the administration would likely reject a French proposal to partially relaunch Iranian oil sales in an effort to salvage parts of the Iran nuclear deal.

Meanwhile, Iranian President Hassan Rouhani on Wednesday removed all limits on nuclear research and development.